法律英语：十二大未解凶杀案

Her name was Elizabeth Short, and she was just 22 years old when, on Jan. 15, 1947, she was found posed naked in a vacant lot in Los Angeles, sawed in half at the waist, drained of her blood, and slit from the corners of her mouth to her ears.

The Case of "The Black Dahlia": 1947

Short's body lies in the grass of the vacant lot. Her murder has been the subject of books and films, many of them offering up theories about who killed her and why — but in real life, the case remains unsolved. Also unclear is how she came to be known in pop culture as "The Black Dahlia" (a dahlia is a flower): One story has it that friends of the raven-haired young woman gave her the nickname, playing off the title of the 1946 film noir The Blue Dahlia. Still others contend the moniker came after her murder, invented by reporters working the salacious case.

Tupac Shakur, Dead at 25: 1996

Clearly, someone had it in for the charismatic, influential rapper/actor. In 1994, he barely escaped with his life after being shot five times by men in army fatigues upon arrival at a New York recording studio. ('Pac publicly theorized that Sean "Puff Daddy" Combs and his protege the Notorious B.I.G. had set him up, an accusation that was never proved but nonetheless ignited the so-called "East Coast-West Coast" rap war.) Then, on the night of Sept. 7, 1996, as Shakur was riding around Las Vegas with his label chief Suge Knight, a white Cadillac pulled alongside their car and an unknown gunman (or gunmen) unloaded about a dozen rounds. Shakur was hit four times and later died at the hospital; Knight was treated for shrapnel that hit his head.

The Notorious B.I.G., Dead at 24: 1997

Less than six months after Shakur's murder, New York rapper Christopher Wallace — a.k.a. the Notorious B.I.G., or Biggie Smalls — risked a trip to Los Angeles to promote his upcoming album Life After Death, despite the fact that he had been receiving threats. On the night of March 9, 1997, while stopped with his entourage at a red light, Wallace was shot in the chest four times by a man driving a black Chevy Impala. The gunman, described as wearing a blue suit and a bow tie, remains unknown. Investigators in both the Tupac and Biggie cases have had little progress in nailing suspects; the LAPD specifically has been accused of not thoroughly investigating possible links to Shakur's Death Row Recrods, and witnesses in both drive-bys have expressed fear about retaliation from the gangs that may be involved.

The Murder of TV's Bob Crane: 1978

He had been the handsome star of the goofy sitcom Hogan's Heroes, but the circumstances of Bob Crane's death seem more fitting for a gruesome CSI-style show: On June 29, 1978, the 49-year-old entertainer was found bludgeoned to death inside an apartment in Scottdale, Ariz……, reportedly with semen on his body.

A prime suspect in Crane's murder was his friend John Henry Carpenter, a video equipment salesman who helped the married Crane make sex tapes with various women. At the time of the murder police found blood in Carpenter's car, but DNA testing was not yet advanced enough to determine whether it was Crane's, and the district attorney declined to prosecute due to insufficient evidence. In 1992 the case was reopened and Carpenter, who maintained his innocence until his death (in 1998), stood trial; he was found not guilty because the evidence had been improperly preserved. A 2002 movie called Auto Focus, starring Greg Kinnear as Crane and Maria Bello as his second wife Sigrid Valdis (pictured, 1974), reintroduced moviegoers to the case, and presented suspicions about Carpenter's role in Crane's death.

The Assassination of Olof Palme: 1986

Palme, the Prime Minister of Sweden and leader of the Social Democratic Party, often angered conservative politicians with views they deemed as pro-Soviet. In 1986, as he was walking home from a movie with his wife, Palme was fatally shot in the back. A small-time drug dealer and criminal was found guilty of the murder two years later, but that conviction was later overturned on appeal. Palme's real killer remains unknown.

The Search for JonBenét Ramsey's Killer: 1996

On the day after Christmas in 1996, Patricia "Patsy" Ramsey woke to find that her 6-year-old daughter JonBenét was missing; she also found a long ransom note demanding $118,000 on a staircase inside the Ramsey home. Later that afternoon, the girl was found dead and covered with a blanket in the Ramseys' wine cellar. She had been strangled to death with a garotte, and also had suffered blunt trauma to the head. Investigators immediately began to suspect JonBenét's parents in her death, and the resulting media circus — mostly focused on JonBenet's participation in child beauty pageants, which many found to be unsettling — kept the wealthy couple under intense scrutiny. Pictured: John and Patsy Ramsey hold up a flyer promising $100,000 reward for information in their daughter's death.

JonBenet Ramsey, Just 6 Years Old Because the Ramseys (and even JonBenét's 9-year-old brother Burke) were under such suspicion, with authorities seemingly looking for evidence that would directly link them to JonBenet's death, is it possible that investigators overlooked crime scene details that pointed in a different direction？ Critics say yes. In 2008, advancements in DNA sampling allowed the Ramseys to be cleared in JonBenét's death — but for Patsy, it was too late: She died in 2006 of ovarian cancer.

In 2006, a former schoolteacher named John Mark Karr told authorities that he had been with JonBenét Ramsey when she died, and that her death was an accident. He was extradited from Thailand for further investigation in Boulder, but was released when his DNA did not match that found on the crime scene. Why did he make a false confession？ "He was trying in every which way to get as close as possible to JonBenét," forensic psychologist Richard M. Swanson told People magazine about Karr, who, according to his brother, was obsessed with the case and even writing a book about it. "By confessing, it says he was actually involved with her."

Jill Dando, Murder of a British Star: 1999

The very popular BBC newsreader was shot point-blank in the back of the head on April 26, 1999, outside her home in West London. Barry George, a man who lived nearby and who had a history of stalking women, was convicted and sentenced to life in prison, but after appealing the sentence George got a new trial and was acquitted. So who was the killer？ Theories starring jealous exes, deranged fans, and even business rivals have swirled for years.

The Cryptic Zodiac Killer: 1968-1969

Between December 1968 and October 1969, at least five people and possibly seven in Northern California died at the hands of a man who called himself the "Zodiac" and who later teased newspapers about his identity by sending letters, some encrypted, for publication. Pictured: a message the Zodiac Killer wrote on a greeting card and sent to the San Francisco Chronicle on Nov. 11, 1969. At the bottom of the letter he lists the months the killings took place, and the total murders he claims (seven).

At the time of the Zodiac murders, Robert Graysmith was a cartoonist at the San Francisco Chronicle, and became intrigued with the mystery of it all, particularly the killer's coded messages. He later wrote a book about his investigations and his obsession with cracking the case; that tome was adapted into a movie called Zodiac (Jake Gyllenhaal plays him). Pictured: Graysmith in 2007 with cryptographs the killer used.

Many (including Robert Graysmith) believe that a man named Arthur Leigh Allen (now dead) was the Zodiac Killer. But in April 2009, a woman named Deborah Perez (pictured) came forward to say that her late father, Guy Ward Hendrickson, was the murderer. Of course, that claim was pretty much dismissed once Perez later insisted that she was the illegitimate daughter of John F. Kennedy.

The Murder of Molly Bish: 2000

While working as a lifeguard at Massachusetts' Comis Pond during the summer of 2000, 16-year-old Molly Bish was kidnapped. The search for her was the largest in state history, but sadly the girl's remains were found in 2003, just five miles from her home. No arrests have ever been made in the case, though a new suspect emerged in February 2009: He is Rodney Stanger, who lived near Bish in Massachusetts at the time of her death, had a car similar to one described as parked near the lifeguard station, fished at Comis Pond, and hunted in the woods where Bish's body was found. He is also currently awaiting trial for the murder of his live-in girlfriend in Florida.

Who Was Jack the Ripper？: 1888

The identity of the person who slashed the throats of poor women in 19th-century London has never been discovered, but theories have run rampant. One even holds that Jack the Ripper was actually a woman. Pictured: Buck's Row in 1888, now Durward Street, where the body of Jack the Ripper's first victim Mary Ann Nichols was found lying across a gutter.

What Ever Happened to Jimmy Hoffa？: 1975

He had been the powerful president of the Teamsters, the largest labor union in the United States, but by 1975 Jimmy Hoffa was struggling to regain his post after doing time for jury tampering and fraud (Richard Nixon pardoned him in 1971). On July 30, 1975, he was due to meet with two Mafia leaders at a suburban Detroit restaurant; he disappeared from the parking lot and was never seen again. Though it's unclear exactly what happened to Hoffa — he was declared legally dead in 1982 — he's spawned an enduring urban legend: that he's buried under an end zone at Giants Stadium (which was under construction at the time of his disappearance).